package org.apache.lucene.index;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;

import org.apache.lucene.store.IndexInput;

final class SegmentTermPositions extends SegmentTermDocs implements TermPositions {
    private IndexInput proxStream;
    private int proxCount;
    private int position;

    SegmentTermPositions(SegmentReader p) {
        super(p);
        this.proxStream = (IndexInput) parent.proxStream.clone();
    }

    final void seek(TermInfo ti) throws IOException {
        super.seek(ti);
        if (ti != null)
            proxStream.seek(ti.proxPointer);
        proxCount = 0;
    }

    public final void close() throws IOException {
        super.close();
        proxStream.close();
    }

    public final int nextPosition() throws IOException {
        proxCount--;
        return position += proxStream.readVInt();
    }

    protected final void skippingDoc() throws IOException {
        for (int f = freq; f > 0; f--) // skip all positions
            proxStream.readVInt();
    }

    public final boolean next() throws IOException {
        for (int f = proxCount; f > 0; f--) // skip unread positions
            proxStream.readVInt();

        if (super.next()) { // run super
            proxCount = freq; // note frequency
            position = 0; // reset position
            return true;
        }
        return false;
    }

    public final int read(final int[] docs, final int[] freqs) {
        throw new UnsupportedOperationException("TermPositions does not support processing multiple documents in one call. Use TermDocs instead.");
    }

    /** Called by super.skipTo(). */
    protected void skipProx(long proxPointer) throws IOException {
        proxStream.seek(proxPointer);
        proxCount = 0;
    }

}
